The present invention relates to collapsible steering assemblies for automotive vehicles, and more particularly to an assembly wherein the steering shaft of the vehicle is mounted within a pair of telescoping support tubes which include a shock absorbing tube interposed therebetween along overlapping portions of the support tubes.
In automotive vehicles, the steering shaft which extends from the steering wheel of the vehicle is generally rotatably supported by the support tubes which are fixed to the vehicle body and which are telescopically mounted relative to each other. A support tube of smaller diameter is inserted into one end of a support tube of larger diameter with the interfitted ends of the support tubes overlapping over a portion of their lengths. A shock absorbing tube having mounted therein steering column balls is interposed between the support tubes at their overlapping portions. In the event of an automobile collision, the driver of the vehicle will collide with the steering wheel and the impact forces thus produced will cause the two support tubes to telescopically contract during collapse of the steering assembly with the shock absorbing tube body operating to lessen the shock imparted to the driver of the vehicle by impact with the vehicle steering wheel.
The steering assembly of a vehicle normally extends downwardly and forwardly from the driver compartment of the vehicle. Accordingly, when the body of the driver is driven against the steering wheel, the force of the impact thus produced upon the steering column involves a force component axially of the steering column as well as a force component which extends perpendicularly to the axial length of the steering column. In conventional shock absorbing steering assemblies, the shock absorbing tube which is interposed between the telescopically interfitted support tubes usually is structured with a wall of uniform thickness throughout. As a result, the steering column balls which are located within the shock absorbing tube will be pressed against the wall of the support tubes with an excessive force and as a result of the balls becoming imbedded in the support tubes there will occur a situation whereby the telescoping relative movement of the support tubes during collapse of the steering assembly will be impeded or prevented. As a result, the driver of the vehicle may be subjected to danger of injury from the shock which will occur upon impact with the steering wheel.
It has been found that in the case of a steering assembly mounted to extend downwardly and forwardly of the driver's compartment, when an automobile collision occurs the force of impact created by the body of the driver of the vehicle will be such that the steering column balls which are located upon the lower rearward portion and the upper forward portion of the shock absorbing tube will be forced into the supporting tubes to prevent the buffer action otherwise occurring during collapse of the supporting tubes.
The present invention is intended to provide a steering assembly which will be more likely to undergo the desired collapsing action when an impact force from the driver is imparted thereto during an automobile collision. The invention provides a shock absorbing tube body which will enable contraction without the steering balls being excessively driven into the surface of the supporting tubes even if a force acting at right angles to the axial direction of the steering shaft is created. Furthermore, the invention is arranged to operate in a manner so as to reduce the clearance which will ordinarily be provided between the interior and exterior telescoping supporting tube by appropriately structuring the shock absorbing tube which is interposed therebetween.